Such a device is, for example, a charge-coupled image sensor device, in which the first insulating layer is a gate dielectric and the conductor strips present thereon constitute gate electrodes. By supplying suitable voltage pulses to the gate electrodes, charge representative of an image to be recorded can be stored in the semiconductor body and this charge can be transported through the semiconductor body.
A semiconductor device of the kind mentioned in the preamble is known from the European Patent Application No. 26376, in which the insulating tracks consist of silicon oxide. The known semiconductor device is manufactured by depositing on a surface of a silicon substrate, provided with a silicon oxide layer, a layer of conducting polycrystalline silicon and a second silicon oxide layer, after which a pattern of insulation strips is formed in the second silicon oxide layer. The pattern is then used in the process of providing by etching the corresponding pattern of conductor strips in the layer of polycrystalline silicon, which is under-etched so that the conductor strips exhibit exposed sides disposed under edges of the insulation strips. Subsequently, the conductor strips of polycrystalline silicon are provided with insulating tracks by converting the exposed polycrystalline silicon into silicon oxide at a high temperature by thermal oxidation.
In the known semiconductor device as described, the choice of conducting materials for manufacturing conductor strips is limited to polycrystalline silicon, and as a result only conductor strips having a comparatively high resistance can be obtained. A further disadvantage of the known semiconductor device as described is that the insulating tracks are manufactured by thermal oxidation of polycrystalline silicon. During this treatment, parts of the silicon oxide layer present on the surface of the silicon substrate which lie between the conductor strips are oxidized further, and as a result the thickness and the depth in the substrate increase. When at this area a second pattern of conductors is formed, electrical pulses at this second pattern will influence charges present in the substrate in another manner than electrical pulses at the first pattern. This is undesirable.
The invention has inter alia for its object to provide a semiconductor device, in which the choice of the conducting materials for manufacturing conductor strips is not limited to polycrystalline silicon and in which the thickness of the first insulating layer is locally influenced only to a small extent during manufacture of the semiconductor device, while its depth remains unchanged.